1. Field of The Invention
The present invention relates to a vehicle movement digital data analyzing apparatus for recording and collecting digital vehicle movement data, indicative of moving conditions of a vehicle such as a speed and a travel distance, onto a record medium and analyzing the thus collected digital vehicle movement data.
2. Description of Related Art
Conventionally, the vehicle movement digital data to be analyzed by a digital data analyzing apparatus of the described type is collected by recording the vehicle movement digital data indicative of moving condition of a vehicle in a recording medium such as an IC memory card removably mounted into an on-vehicle digital data recording apparatus, having such data subjected to a compression processing according to predetermined values. The vehicle movement digital data collected through the above described recording of data is read by a vehicle movement digital data analyzing apparatus provided in the office which controls the vehicle movement and subjected to an expansion processing, and then used for various analyses.
The recording of the data in the recording medium is performed according to the format, for example, as shown in FIG. 7.
Referring to FIG. 7, reference character M denotes a memory in which one word is structured of eight bits (one byte). In the memory, there are formed a data region M.sub.1 and an ID region M.sub.2. The data region M.sub.1 is further divided into a distance data recording region M.sub.11 partitioned into sections, each section corresponding to each vehicle movement used for successively recording therein the travel distance data compressed by a predetermined compression method, and a speed data recording region M.sub.12 also partitioned into sections, each section corresponding to each operation, used for successively recording therein the speed data compressed by the predetermined compression method. One movement is defined, for example, as the time interval between the mounting of an IC memory card into the vehicle movement digital data recording apparatus and the removing of the same from the recording apparatus.
In the ID region M.sub.2, there are also recorded such data as the allowance, resolution, and sampling time for each movement, and addresses in the regions M.sub.11 and M.sub.12 at which the final data of the travel distance data and the speed data for each movement are recorded. The aforesaid allowance represents the error range allowed at the time of recording, while the resolution and the sampling time are data related to precision of the collected speed data. The precision of the data obtained by the compression processing depends on the allowance, resolution, and sampling time in the speed data compression, and these data are absolutely essential for data expansion and analysis on the analyzing side.
In the speed data region M.sub.12 of the data region M.sub.1, there are recorded the starting time and the ending time at the start and the end of each movement. such time data are important when analysis is made with the speed data distributed over the period between the starting time and the ending time to thereby find out the state of speed at each point of time in-between.
The recording medium having the movement data recorded therein as described above is then removed from the vehicle movement digital data recording apparatus and mounted into the analyzing apparatus for analyzing vehicle movement digital data. Thereby, analyses of each movement are made. As one of the results provided by such analytical processing, the momentarily varying vehicle speed during each movement is arranged in the form of graph to be displayed on the screen of the CRT or printed in a sheet of paper so that the moving condition is seen at a glance.
More specifically, the vehicle movement data recording apparatus is constituted from a microcomputer. The microcomputer samples and receives an electric signal generated from a rotation sensor connected to a transmission of the vehicle by a suitable connecting means and having a period conforming to rotation of an axle of the vehicle and determines an instantaneous speed and a travel distance of the vehicle by calculation in accordance with the thus received electric signal. Then, in order to record the instantaneous speed and travel distance obtained by such a calculation as digital data onto a record medium loaded on a card writer, the microcomputer further executes data compression processing for decreasing the data length of the instantaneous speed and travel distance.
Meanwhile, the analyzing apparatus is constituted from a personal computer (PC) and a reader-writer (RW) connected to the personal computer. If the record medium is loaded into the read-writer, then vehicle movement data recorded on the record medium are read out by the read-writer and transmitted to and stored into a memory in the personal computer. The data thus stored in the memory are expanded and analyzed in accordance with an analyzing program and recorded onto a floppy disk (FD).
As one of the results provided by such analytical processing, the speed data, for example, subjected to expansion processing is graphically displayed on the screen of a CRT. If the data for 24 hours are all displayed on one screen, the details of the display become quite difficult to distinguish, and therefore, an enlarged display of a part of the data has come to be practiced. It is also practiced to have the 24-hour graphical display or the enlarged graphical displayed on the CRT screen printed on a sheet of paper using a printer.
In the case where the enlarged graph is printed, the graph printed on the printing paper is that of one screen. Therefore, when it is desired to view the entire graph in an enlarged state, the enlarged graphs immediately preceding and following the current enlarged graph are displayed and additionally printed. In such case, it becomes necessary to output the adjacent data onto the CRT continuously to the current data. To achieve this, the scrolling function has been conventionally used. The conventional scrolling function is such that causes the graph on the screen to be moved backward or forward in units of one dot (pixel) by manual operation.
When using the above described scrolling function, however, it is very difficult to bring the end or the start of one screen into coincidence with the start or the end of another screen adjacent thereto. Therefore, supposing that the screen shown in FIG. 8(a) is a preceding screen and the screen continuing thereto is as shown in FIG. 8(b), the screen actually obtained by shifting the screen by means of the scrolling function frequently becomes such as shown in FIG. 8(c), that is, the portion of the screen in the range D shown therein becomes missing; otherwise, screens having overlapping portions are obtained. Thus, there has been a problem that the graphs obtained by printing such screens produce discontinuity therebetween.